AbstractConversion of lignocellulosic biomass‐derived 5‐(Hydroxymethyl) furfural (HMF) into 2,5‐Furandicarboxylic acid (FDCA) has a high potential to replace petroleum‐based feedstocks for the production of plastics. In this study, a green synthesis strategy for the selective oxidation of HMF to FDCA is reported by using laser‐generated and specifically designed bimetallic AuAg nanoparticle catalysts supported on Al2O3 using molecular oxygen as oxidant and water as a solvent. Although supported AuAg catalysts are already known as suitable catalysts for this reaction, the optimal reaction conditions (type of base, reaction temperature, oxygen pressure), Au : Ag composition, role of metal‐support effects and origin of the active site still remain under debate. Interestingly, an Au9Ag1/Al2O3 catalyst exhibited the highest activity with a FDCA yield of up to 66 % at 80 % HMF conversion. Hereby, NaHCO3 (instead of NaOH) as a smoother base in 2 : 1 base:HMF ratio, low oxygen pressures of 5 bar, and a mild temperature of 150 °C were found optimal. The yield remained fairly stable on reuse of the catalyst for 3 cycles without hints of catalyst sintering or leaching. The titration of surficial hydroxyls on the AuxAgy/Al2O3 surface showed the highest density of acidic hydroxyls for the most active Au9Ag1/Al2O3 catalyst. The respective hydroxyls potentially originate from metal‐support interactions between the AuAg nanoparticles with the alumina support and act as Lewis acidic sites that oxidize the alcohol moiety of HMF to form FDCA with high selectively. In summary, this study shows that the catalytic activity of AuAg catalysts in HMF oxidation is not just linked to an alloying effect but also to a metal‐support effect where the AuAg nanoparticles appear to directly affect the local acidity of the support.
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